are and what we are. >> there's nothing else like it. >> "boston globe"reporterstevesilvawas at the starting line of the day's biggest event, the boston marathon. >> part of the american sports scene since 1897. >> it was a chilly morning, 30 degrees, people starting to warmup, unlike last year where it was 80 degrees. the weather's not going to be a story this year. what's going to be the story? >> for pediatric resident natalie stavas, it would be a story of giving back. >> it was a very special day for me. i had decided to raise money for boston medical center pediatrics. >> doctors told chris that this was a day her daughter might not ever live to see. >> they said her prognosis was, you know, maybe she'll be 10 if we were lucky. >> the mitochondrial disease that weakened kayla's cells made her terribly ill. >> those first few years were hard, she needed to have medical procedures, time in the hospital, lots of pneumonias. >> for the kay girls, it had been a tough go. kayla's health challenges, two benign brain tumors for chris, the loss of kayla's father, chris' husb